String

String Buffer

• Java StringBuffer class is used to create mutable (modifiable) String objects.
• The StringBuffer class in Java is the same as String class except it is mutable i.e. it can be changed.

StringBuffer constructors

• StringBuffer()
• It reserves space for 16 characters.
For ex:
StringBuffer s = new StringBuffer();
System.out.println(s); =>

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• StringBuffer(int size)
• It sets the buffer of initaially specified size.
For ex:
StringBuffer s = new StringBuffer(25);
System.out.println(s); =>

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• StringBuffer(String str)
• It sets the initial contents of the StringBuffer object and reserves room for 16 more characters.
For ex:
StringBuffer s = new StringBuffer("CCIT");
System.out.println(s); => CCIT

String method

• StringBuffer append(String s)
• It is used to append the specified string with contents of StringBuffer.
• It returns reference to same object.
• The append( ) method is overloaded to add char , int , float etc.
• append(char val)
• append(Boolean val)
• append(int val)
• append(float val)
• append(double val)
For ex:
StringBuffer s = new StringBuffer();
s.append("shree") ;
s.append(420);
System.out.println(s); => shree420

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• StringBuffer insert(int index,String s)
• It is used to insert the specified string at the specified position.
• It returns reference to same object.
• The insert( ) method is overloaded to insert char , int , float etc.
• insert(int index,char val)
• insert(int index,boolean val)
• insert(int index,int val)
• insert(int index,float val)
• insert(int index,double val)
For ex:
StringBuffer s = new StringBuffer();
s.append("RamSeeta");
s.insert(3,"Laxman");
System.out.println(s); => RamLaxmanSeeta

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• StringBuffer replace(int startIndex,int endIndex,String str)
• is used to replace the string from specified startIndex to endIndex with given string.
• Including startindex and excluding endindex.
• It returns reference of same object.
For ex:
StringBuffer s=new StringBuffer("CCIT Rajapeth Amravati");
s.replace(5,13,"Gadge Nagar");
System.out.println(s); => CCIT Gadge Nagar Amravati

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• StringBuffer delete(int startIndex,int endIndex)
• is used to delete the string from specified startIndex to endIndex.
• Including startindex and excluding endindex.
• It returns reference of same object.
For ex:
StringBuffer s=new StringBuffer("CCIT Rajapeth Amravati");
s.delete(5,13);
System.out.println(s); => CCITAmravati

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• StringBuffer reverse()
• is used to reverse the contents of StringBuffer.
For ex:
StringBuffer s1=new StringBuffer("amravati");
s1.reverse();
System.out.println(s1); => itavarma

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• char charAt(int index)
• returns char value from specified index.
For ex:
StringBuffer s1=new StringBuffer("Amravati");
char ch= s1.charAt(2);
System.out.println(ch); => r

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• String substring(int beginIndex)
• returns a substring
• Starting from beginIndex upto end.
For ex:
StringBuffer s1 = new StringBuffer("Amravati");
String s2 = s1.substring(4);
System.out.println(s2); => vati

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• String substring(int beginIndex,int endIndex)
• returns a substring
• Staring from beginIndex upto endIndex
• Including beginIndex and excluding endIndex.
For ex:
StringBuffer s1 = new StringBuffer("Amravati");
String s2 = s1.substring(2,4);
System.out.println(s2); => ra

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• int length()
• is used to return the length of the string i.e. total number of characters.
For ex:
StringBuffer s = new StringBuffer("CCIT");
int n = s.length();
System.out.println(n); => 4

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• int capacity()
• is used to return the current capacity.
For ex:
StringBuffer s = new StringBuffer();
int n = s.capacity();
System.out.println(n); => 16

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• void ensureCapacity(int minimumCapacity)
• is used to ensure the capacity at least equal to the given minimum.
For ex:
StringBuffer s = new StringBuffer();
s.ensureCapacity(100);
int n = s.capacity();
System.out.println(n); => 100